Open position: Senior Process Systems Engineer

About AquaGreen

AquaGreen is an impact-driven Danish CleanTech company and a leader in advanced drying and pyrolysis technology for biosolids. Our ambition is to become the global leader in carbon-negative and energy-neutral conversion of biosolids into biochar. Our patented solutions reduce environmental pollutants, enable recycling of scarce nutrients, store carbon in biochar, and create sustainable value for wastewater utilities worldwide. We are currently building the foundation for rapid international scaling supported by strong global investors.

The Position

We are seeking a Senior Process Systems Engineer to analyse, understand, and optimise the process performance of our integrated steam drying and pyrolysis plants. The role sits at the intersection of process design and plant operation in a complex thermochemical processing system.

At the core of the role is a deep command of the plant's mass and energy balances – not only on paper, but as they behave in real plant operation. You will analyse operational data, develop and maintain mass and energy balances, understand process dynamics, and translate this understanding into safe, stable, and efficient plant operation – including the control strategies that support it.

Programming of the control logic is handled by the automation team; your key contribution is the process understanding and the functional documentation – process descriptions, sequence logic, and Functional Design Specifications (FDS) – that enables the automation team to implement it, working closely with other functions such as mechanical engineering and the installation & commissioning team.

Your Primary Responsibilities

Develop a deep understanding of the process in our integrated steam drying and pyrolysis plants, including the interaction between:

The overall mass balance incl. the core drying and pyrolysis processes
Heat and energy flows
Process parameters and plant control strategies

Participate in development projects, both conceptual and sub-system, as Process Lead, ensuring alignment between process design and automation

Analyse and optimise process dynamics, identifying factors that influence plant stability, operability, and performance

Translate process understanding into clear, high-level control philosophies and regulation strategies together with the automation team

Contribute to the definition and documentation of the process control and subsequent functional control logic in collaboration with the automation team, including:

Control and regulation strategies
Process sequences and operational states
Alarm strategies and operational logic
Interlocks and safety functions where relevant

Analyse operational data to identify bottlenecks, operational constraints, and improvements in plant stability, energy efficiency, gas and biochar production, and overall plant capacity

Work closely with the engineering and service team to translate analysis into practical improvements in plant operation on site

Contribute to the design and evaluation of process development, modifications and improvements, including within current development areas:

Flue gas cleaning – meeting increasing requirements in customer projects for removing pollutants (SOx, NOx, …) from flue gases
Return water cleaning – meeting increasing requirements in customer projects for removing pollutants from return water (heavy metals, nitrification inhibitors)
Combustion and pyrolysis – soot reduction, burner optimisation, and reduction of pulsations/buffeting
Sludge drying – characterising how sludge rheology, viscosity, and stickiness influence our steam drying process
Biochar – phosphorus extraction and working with partners to valorise the output product

Professional Qualifications

Strong understanding of industrial process plants and thermochemical processes

Hands-on experience with energy or process plants is essential

Deep understanding of dynamic mass and energy balances, and how they behave under real operating conditions

Experience with or strong understanding of:

Process dynamics and control
The interface between process engineering and automation systems
Ability to analyse and interpret operational data from industrial process plants
Good working understanding of control systems and process control logic
Ability to define and document control strategies and functional logic for the automation team to implement; experience preparing such control documentation is an advantage
A track record of applying process knowledge to deliver stable and efficient plant operation
Strong analytical and systems-level thinking

Education and Background

The position requires strong theoretical process understanding combined with a practical interest in industrial plant operation – you are keen to go to sites to understand the plant dynamics in detail.

You will typically hold:

A relevant educational background, e.g. PhD, M.Sc., B.Sc. or similar, in fields such as:

Chemical Engineering
Process Engineering
Energy Engineering
Mechanical Engineering with specialisation in thermal systems

Experience with energy plants, or the process industry is essential. In addition, experience with the following is a plus:

Thermal processes – not least pyrolysis and/or gasification
Industrial process control and plant operation

Process simulation tools, digital twins, AI tools or similar

Wastewater treatment – an understanding of the utilities and treatment processes our biosolids originate from

Upstream sludge handling – e.g. de-watering, municipal sludge, and sludge composition analysis
Emission control – e.g. carbon filters, scrubbers, and NOx suppression systems

Above all, we are looking for someone who can make complex process systems legible – and turn that insight into stable and efficient plant operation.

What Success Looks Like After 12 Months

Within your first year, we expect you to have built and documented a solid command of our plants – how they behave, what drives performance, and where the control levers are.

Concretely, you will be able to:

Understand and work actively with the mass and energy balances of the process across our plants and projects

Identify the key process parameters governing plant performance

Have played a key role in producing and documenting control philosophy and functional description that the automation team is actively implementing

Establish strong collaboration with the automation team around implementation of control strategies

Be a recognised process authority that engineering, automation, and operations teams turn to for process questions

Have initiated or delivered at least one concrete improvement to plant stability, energy efficiency, throughput, or control, with a measurable effect on performance

We Offer

A central technical role in an innovative technology company

The opportunity to work with advanced process engineering in a unique pyrolysis plant

A high degree of professional autonomy and the opportunity to influence the development of the plant

Close collaboration with engineering, operations, projects, and management

A highly dynamic and energised scale-up environment, where the process from idea to decision is short and efficient

Workplace at Meterbuen 27A, 2740 Skovlunde, Denmark
Salary and employment terms commensurate with experience and qualifications

Application

Hiring Manager and Contact person: Rune Skovgaard-Petersen, Chief Technology Officer, rusp@aquagreen.dk, +45 51 22 61 12

We will continually review incoming applications during August, deadline is 24^th of August, whereafter the selection and interview process will take place.

Engineered for long-term carbon sequestration

HECLA® Setores (Sewage to Resources) transforms biosolids management by turning wastewater sludge into a valuable carbon-rich resource. The integrated steam-drying and pyrolysis solution enables wastewater treatment plants to produce high-value biochar while permanently sequestering carbon.

Learn more about Hecla® Setores